The power battery of an electric vehicle or a hybrid electric vehicle comprises two parts: a starting battery and a traction battery. The starting battery is used to start the engine or motor of the vehicle, or to supply power to the vehicle body electric system before starting the vehicle. The traction battery is used to supply power to the motor after starting the vehicle, and the supplied power drives the motor to rotate the vehicle wheels.
The conventional in-vehicle charger of the electric vehicle or the hybrid electric vehicle only charges the traction battery. When the electric vehicle or the hybrid electric vehicle has not been started in a long time, the starting battery may feed power as a result of the static power of the vehicle body electric system. Although the electric energy of the traction battery may be converted and input to the starting battery via a DC/DC converter, the traction battery itself may also feed power due to self-electricity consumption or static power of the electrical apparatus connected with the traction battery. The starting battery and traction battery are simultaneously in feedback electricity state, which is required for charging both the traction battery and the starting battery. However, it may not be feasible to convert and input the electric energy of the traction battery to the starting battery via the DC/DC converter due to low voltage in the vehicle body electric system. The low voltage may be a result of the battery manager needs of the power supply during the charging process, and the feeding of the traction battery. Thus, the conventional in-vehicle charger may not be able to charge the traction battery when the starting battery and traction battery are simultaneously in feedback electricity state.